Passive restraint devices known as air bags frequently are used in automobiles to reduce occupant (driver or passenger) injuries and/or fatalities that result from vehicular accidents. As is known in the art, air bag restraint systems restrain forward movement of the occupant to protect him or her from contact with the interior of the vehicle by instantaneously inflating to cushion the occupant. Generally speaking, air bag systems comprise an inflater for releasing a gas (e.g., nitrogen), a bag to be inflated by the released gas, a housing enclosing the inflater and the bag, a sensor detecting a collision of greater than a predetermined magnitude, and a control system that transmits a signal to the inflater to activate inflation of the bag. When the gas is released from the inflater, it fills the bag to exert an inner pressure upon the interior walls of the bag, which urges the bag to inflate.
Ironically, although air bags are intended to prevent injuries, air bags themselves can cause occupant injuries and even fatalities, especially when the occupant is relatively small or frail (e.g., children, the elderly). The primary reason for these injuries, is the high speed and pressure at which such air bags deploy (e.g., 200 mph, 34 psi) as well as the particular part of the person's body that impacts the air bag. Normally, it is the face and neck of such an occupant that bears the brunt of this impact.
In response to the occurrence of such injuries, several manufacturers have begun development of so-called "smart" air bags. Generally speaking, smart air bags use some form of sensing device to determine certain physical characteristics of a vehicle occupant that is to be cushioned by the bag if the vehicle were involved in an accident. For example, if it is determined by the sensing device that the occupant is small in size and/or weight, the air bag is either temporarily disabled or is adjusted to inflate with less force to avoid injuring the occupant. Although such smart air bags may prevent typical air bag injuries, their use could permit more common vehicular injuries to occur. In the case of the temporarily disabled air bag, no buffer whatsoever is provided between the occupant and the vehicle interior to cushion the occupant. As for the less forcefully deploying air bag, it is possible that inflation may not occur quickly enough to fully cushion the occupant, or that the air bag may not inflate to the degree necessary to fully protect the occupant.
From the above, it can be appreciated that it would be desirable to have a method and apparatus for controlling air bag deployment that provides for complete cushioning of the occupant in a vehicular accident with less risk of occupant injury caused by the air bag's deployment.